Penicillin

Little Roscoe Bartlett was approaching two years old when a Scottish scientist named Alexander Fleming discovered penicillin. By 1931, he concluded that the stuff couldn't last long enough in the human body to do any good, so he stopped studying it. It wasn't until 1942 that a single patient was successfully treated for streptococcal septicemia, and it took half of the US supply of penicillin to do it. A year later, scientists found that a moldy cantaloupe in Peoria, Illinois contained the best penicillin in the world. After that, millions of doses were able to save countless American lives in World War II.